Nitrox mixtures are a popular form of oxygen enriched breathing gas used in diving applications. In its basic form, Nitrox is a mixture of oxygen (O2) and nitrogen. Nitrox has the advantage of lengthening no-decompression limits, shortening surface intervals, and providing an added safety buffer for decompression sickness in certain circumstances.
Diving with nitrox, however, exposes the diver to higher partial pressures of oxygen (PO2) during a dive, even at recreational depths. Considering a maximum recreational depth of 40 meters and a nitrox mixture of 40% oxygen, the partial pressure of oxygen is 1.6 bar at 30 meters. Oxygen becomes toxic above 1.6 bar. Oxygen intoxication can lead to convulsions, which if they occur during a dive, can be fatal.
Nitrox is a prepared gas, and for safety reasons, the fraction or percentage of oxygen (FO2) is written directly on the tank. This allows a diver to select the appropriate nitrox concentration when preparing for a dive. However, there is always a risk that tank may be improperly filled or improperly marked. As a result, divers must analyze the gas of their diving tank before a dive. In some countries it is mandatory for divers to conduct this analysis themselves and fill out a protocol. To conduct such an analysis, the diver uses a nitrox analyzer.
A typical nitrox analyzer is a separate device containing an oxygen sensor. In use, a diver decants gas from their tank and flushes the oxygen sensor of the nitrox analyzer with the decanted gas. The nitrox analyzer contains a display which then provides a reading of the fraction or percentage of oxygen.
While such nitrox analyzers provide a means for ascertaining FO2, the above devices and process is now without its drawbacks. For example, analyzing nitrox is time consuming and requires a separate device, i.e. the above mentioned nitrox analyzer. Further, a user may incorrectly use the analyzer, resulting in an incorrect reading. Still further, after the analysis is completed, the information collected must be archived.
After correct analysis of the breathing gas, the diver has to enter the O2 fraction into the dive computer. This is required, so that the dive computer can correctly calculate the inert gas fraction of the breathing gas, and then correctly calculate inert-gas tissue loadings. This is a time consuming step. Moreover, this is also another failure source—if the diver makes a mistake by entering the incorrect O2 faction into the dive computer, the dive computer is unable to perform correct decompression calculations, which may lead to decompression sickness.
The above issues also persist for deeper diving applications which utilize other types of gases, such as those containing helium. In such applications, the gas must tested as in the above example pertaining to nitrox. This testing is done using a separate analyzer in a similar fashion as mentioned above. However, both helium and oxygen percentage levels must be tested which is even more time consuming. Further, such analyzers capable of analyzing helium as well are considerably costly.
It is also good practice to analyze breathing gases for contaminants prior to a dive. Such contaminants may include among others carbon monoxide (CO), carbon dioxide (CO2), oil, or water. Even small amounts of CO may lead to carbon monoxide poisoning, which may be fatal. Further, a high water content in the breathing gas may lead to freezing of the breathing regulator in cold-water diving, which is also problematic. Many breathing gas filling stations have sensors to continuously check the quality of the breathing gas, however there are also many filling stations who do not have such systems. The diver must resort to portable reusable or single use systems, similar to a nitrox analyzer described above.
Accordingly, there is a need in the art for a system for automatically analyzing the constituents of a breathing gas, so that possible user errors can be excluded and safety can be increased. It would also be highly advantageous if such a system also automatically communicates with a dive computer regarding the information collected so that minimal to no user intervention is required prior to a dive to reduce pre-dive preparation time. The invention provides such a system. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.